Advances in the Diagnosis and Treatment of HF: Focus on CAD Prevention

Advances in the Diagnosis and Treatment of HF: Focus on CAD Prevention

BOCA RATON, Fla—“Heart failure is similar, whether it is due to ischemic heart disease or caused by underlying intrinsic heart muscle disease without ischemia. Therefore, management is very similar up to the point of making a decision about whether revascularization will be useful in resolving the heart failure,” Jeffrey S. Borer, MD, Harriman Professor of Cardiovascular Medicine at Cornell University’s Weill Medical College, New York City, said at the 9th Annual Meeting of the Heart Failure Society of America.

Dr Borer presided over a symposium on the diagnosis and management of coronary artery disease (CAD) in heart failure (HF). A variety of techniques, including echocardiography, radionuclide imaging, and magnetic resonance imaging could today be used to identify the patients who have large-vessel CAD and who might respond if a procedure were performed to remedy the problem.

More than two thirds of patients who end up with HF have CAD, which is the underlying cause for the eventual HF. Robert O. Bonow, MD, chief of cardiology, Northwestern University Medical School, Chicago, noted that because of the progressive nature of CAD, the resultant HF is often more aggressive and accelerated than HF from other causes.

The 3 major etiologies of HF are, in order of frequency:

• CAD
• Cardiomyopathy
• Hypertension

Hypertension as cause of HF is especially prevalent among blacks and women. All multicenter trials conducted in the developed world have demonstrated that >60% of patients with HF have CAD, either alone or with hypertension.

“This means,” Dr Bonow told IMWR, “that the diagnostic tools we use need to be specific for coronary disease and secondary prevention.”

Jonathan R. Lindner, MD, of the University of Virginia, evaluated the viability of echocardiography with dobutamine (Dobutrex), a diagnostic tool that increases the contractility of the heart. Dr Lindner, who has been investigating cardiac viability and the presence of ischemia in patients with systolic dysfunction, told IMWR, “We look at the contractile patterns of the heart, and from the data that I have seen, there is a blurring of the lines in terms of knowing how much alive tissue there is and how much ischemia there is.” He added that this finding indicated that “dobutamine is of limited use. [However], there are other ways of looking at the heart—new techniques in echocardiography that may actually be able to overcome this.”

One of these techniques is strain-rate imaging, which looks at the rate of the deformation of the 3-dimensionally of the heart—longitudinally, circumferentially, and radially. Strain-rate imaging may be able to detect changes in the heart that are not solely due to what is going on in the endocardium. It is based on tissue velocities, a measure of diastolic performance. The technique has also been adapted to specifically look at systolic performance and the contractile patterns of the heart, but it is not yet uniformly used.

Another technique looks at the perfusion of the heart. “Using microbubble tracers in a type of imaging called contrast echocardiography, we are able to tell viability in the heart by taking a look to see whether there is intact microcirculation and, at the same time, seeing whether there is ischemia by doing stress testing and reviewing absolute patterns of blood flow,” said Dr Lindner.

Imaging of the heart plays a crucial role in making treatment decisions, as well as in diagnosis. Vasken Dilsizian, MD, of the University of Maryland in College Park, noted that after a heart attack, when there is a thinning of the cardiac muscle, the contralateral portion of the heart becomes thicker and the entire shape of the heart changes.

Dr Dilsizian said that “with the ventricle ‘remodeled’ after a myocardial infarct, the heart may get to a point of no return, where transplantation may be the only option. Unfortunately, the presentation of patients who can completely recover from heart failure may appear the same way. Imaging modalities can differentiate prospectively which patients have potential recovery of function after revascularization.”

Dr Borer urged physicians to look for coronary disease in patients with HF.

However, there is still the unanswered question: Are there important pathophysiological differences that might call for different medical therapies in patients who do not have large-vessel CAD with HF?

Therefore, “the take-home message would be, if you see a patient with heart failure, make every effort to determine if the patient has large- vessel coronary artery disease associated with his heart failure, because additional diagnostic and therapeutic options, besides giving medication, may be useful for a patient with large-vessel coronary disease,” Dr Borer said. “There are diagnostic procedures today that can determine whether the patient has large-vessel CAD, and other procedures that can determine the likelihood of that remedy having a positive impact,” he noted.

Therefore, determining the etiology of HF by use of imaging modalities is a way to ensure the correct approach to treatment. —L.D.